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AGU 2008: Evidence that Antarctica has warmed significantly over past 50 years [updated]

The research below, which I blogged from the AGU conference in December, is published today in Nature [subscription].

New research presented at the AGU today suggests that the entire Antarctic continent may have warmed significantly over the past 50 years. The study, led by Eric Steig of the University of Washington in Seattle and soon to be published in Nature, calls into question existing lines of evidence that show the region has mostly cooled over the past half-century. [Update: To be more specific here, incomplete records previously suggested that the interior was cooling].

Steig and colleagues combined satellite thermal infra-red collected over 25 years with weather station data for the region. Although the satellite data span a shorter time period and are accurate only for blue sky days i.e. when there is no cloud cover, they provide high spatial coverage of the region, which cannot be obtained from discrete ground measurements. In contrast, the weather station data provide complete temporal resolution over the past half-century.

Using an iterative process to analyse the data, they found warming over the entire Antarctic continent for the period 1957-2006. Restricting their analysis to 1969 to 2000, a period for which other studies have found a net cooling trend, Steig’s study found slight cooling in east Antarctica, but net warming over west Antarctica.

As well as uncovering evidence of warming over a wider region than previous studies have shown, the researchers found that warming occurred throughout all of the year and was greatest in winter and spring. In contrast, cooling over east Antarctica was restricted to autumn.


They independently confirmed these trends by using data from automatic weather stations, and excluding the satellite data.

Overall, the study suggests that warming is not limited to the Antarctica peninsula region. Steig says their findings are backed up by recent results from David Bromwich of the Byrd Polar Research Centre at Ohio State University also presented at this meeting and by a climate modelling study using data assimilation from Hugues Goosse of the Université Catholique de Louvain in Belgium and colleagues, which is due to be published in the journal Climate Dynamics.

The authors speculate that the warming trend may be due to shifts in circulation coupled with sea ice changes.

Olive Heffernan

Comments

  1. Report this comment

    Ron Cram said:

    It would have been nice if this report had quantified the warming trend. I wonder how significant the warming trend can be when everyone else has seen cooling? At least the authors are not blaming the warming on nature and not atmospheric CO2.

  2. Report this comment

    Mark Smith said:

    So how does this affect the GCMs?

    From Real Climate, wrt to the idea that Antarctica has been cooling:

    “Doesn’t this contradict the calculations that greenhouse gases are warming the globe? Not at all, because a cold Antarctica is just what calculations predict… and have predicted for the past quarter century.”

  3. Report this comment

    John M said:

    I’m very confident that climate scientists will eventually be able to tell us whether Antarctica is cooling, warming, or not changing in temperature.

    I’m also quite confident that, which ever one it is, it will be “consistent with” the models.

  4. Report this comment

    Philip Machanick said:

    John M, here’s the RealClimate article Mark Smith cited: http://www.realclimate.org/index.php/archives/2008/02/antarctica-is-cold/

    The claim is not that the Antarctic would cool indefinitely but that cooling was possible because of the nature of ocean circulation. Up to 50 years, cited from a 1988 paper, was the specific possibility.

    That warming is happening faster than expected is hardly cause for glee. The entire “sceptic” movement has been premised on the view that the standard climate models are “alarmist”. Increasingly often, the data supports the opposite conclusion: that they are too optimistic.

  5. Report this comment

    John M said:

    Philip,

    So has the Antarctic cooled or warmed over the last fifty years and which would be consistent with the models?

    Just want to get one or the other on record.

  6. Report this comment

    al dionne said:

    What I think is certain here is that 50 years from now climate scientists still won’t agree what the temperature trend is in Antarctica.

    Why? Because more uncertainty breeds demand for more study and we know what that means.

    The climate change community gets most of their funding from government or government supported institutions and the government gets ALL of their money from me so this is really just a massive transfer payment scheme.

    Isn’t it always about money?

    Its not like this is a big conspiracy. People like Al Gore don’t even bother to hide their “fund raising” agenda.

    The idea that anthropogenic contributions are statistically significant to natural climate change is laughable to any reasonable person with even a vague knowledge of earth’s history.

    But lets just say for a moment all you Climate Change Alarmists (CCA’s) are correct. (Yeah, don’t play dumb—you know who you are)

    What’s your solution? Well ultimately I’ll have to hand over my entire paycheck to Al Gore and the “scientific community”

    and return to my cave while you guys fix everything.

    Aren’t any of you capable of offering a political solution that is not politically impossible?

    Of course not. So since you’re unable to persuade me you’ll ultimately just have to use force. Government Force.

    All of it for my own good and the good of the planet of course. I recommend you seize the moral high ground by wearing green arm bands instead of the red ones with the black spider.

    Does any of this sound familiar?

    Yeah, I didn’t think so…….

  7. Report this comment

    Killian O'Brien said:

    John M., I don’t understand how childish sarcasm is supposed to help move the discussion forward. Why pretend changes in data are proof of failure? Ridiculous and illogical.

    We’ll have to wait and see if this info is further replicated, but common sense tells us the Antarctic must begin to warm if the rest of the planet is warming, which it is. It would seem the circumpolar winds don’t isolate the continent as much as previously thought.

    Best hopes for more honest debate.

    Cheers

  8. Report this comment

    John M said:

    Killian,

    I’m sorry you find my confusion over whether a warming or cooling Antarctica is “consistent with” GCMs to be childish. You see, I come from another field of science where folks don’t get insulted if someone asks “will A cause B or will it cause C, and how can we tell the difference?” Practioners of this other science are actually even known to utter the phrase “I don’t know” on rare occasions. And I have the utmost respect for careful data gatherers, regardless of where it leads them and regardless of whether their findings contradict other findings. The problem I have is when, regardless of the finding, it is considered to be “consistent with” global warming or climate change.

    I am also somewhat callow when it comes to whether more snow in the Alps or less snow in the Alps is a sign of global warming, or whether the “global cooling” in the 70s caused the same droughts in Africa and the same extreme weather in North America that global warming is now causing, at least according to highly respected professional journalists, but I digress.

    For a more mature view on whether anything and everything is “consistent with” the GCMs and global warming, I refer you to the much more sophisticated thoughts of Roger Pielke Jr.

    http://sciencepolicy.colorado.edu/prometheus/archives/climate_change/001416the_consistentwith_.html

  9. Report this comment

    Sierra Summit said:

    Nature.com blogs about climate change and California

    Nature magazine’s new online climate page has an interesting blog post about global warming and California. The Golden State has long been a climate policy leader, the blog points out. But such leadership, it adds, is also a matter of…

  10. Report this comment

    Bob Tisdale said:

    Here’s a comparative graph of CRUTEM, GISTEM and NCDC surface station temperature anomaly data for the Antarctic with common base years of 1971 to 2000:

    http://i39.tinypic.com/33nkxfc.jpg

    Why pick 1957 as the start date? The peak is in June/July 1956. Present temperatures are lower than they were in 1956. The trough is in October/November 1958.

    And why is it that the ERSST.v3b version of SST anomalies for the Southern Ocean seems to contradict any discussion of warming at high latitudes in the Southern Hemisphere. Looks like SST anomalies are showing an overall decrease over the past 120+ years.

    http://i44.tinypic.com/2uen29u.jpg

  11. Report this comment

    PaulM said:

    Here is a reminder of some of the considerable evidence that Antarctica is cooling, not warming:

    (a) Satellite data from UAH and RSS shows cooling.

    (b) Antarctic sea ice is increasing.

    © Station data shows no trend (eg at the Amundsen-Scott base) or cooling (eg at Halley).

  12. Report this comment

    Bob Tisdale said:

    Figure 2 in the study made me curious, so I retrieved CRUTEM, GISS, and NCDC Surface Temperature data (January 1950 to Dec 2008) for the West Antarctic (available through the KNMI Climate Explorer website).

    http://i40.tinypic.com/vp7pdt.jpg

    There are two things that stand out, excluding the obvious dissimilarities between the data:

    1. During periods of volcanic activity (excluding El Chichon), year-to-year variability appears to decrease. That difference could bias the trends. How was this addressed by the researchers?

    2. The NCDC and CRUTEM data appear to have step changes that could be linked to the 1982/83 and 1997/98 El Nino events. These steps also appear in Cell B of the report’s Figure 2, though there they are skewed by the smoothing. How did the researchers account for the ENSO-induced step changes?

  13. Report this comment

    George Tobin said:

    This study also appears to confirm that like the rest of the planet, whatever warming has or has not taken place in Antarctica appears to have leveled off or declined for the last decade.

    The breathless media attention (BBC, Newsweak) conveys the false impression that an accelerating trend of some kind has just been discovered. However, the simple fact is that a rather questionable method with an error range several times bigger than the reported amount of temperature change has inferred a rather modest increase (by alarmist standards) in average temperature in only one part of that continent. Pretty thin soup regardless of one’s climate issue orientation.

    Like other commenters above I also remember the appearance-saving spin on RC regarding reports of Antarctic cooling being “consistent with” AGW which makes this latest non-story just another Heads-I-Win Tails-You-Lose alarmist spinfest. It’s tiresome.

  14. Report this comment

    Malcolm said:

    A questionable methodology which produces results that contradicts all the models is no way to convince a growing sceptical public that global warming should be taken seriously.

    If the authors of this study thought that they were doing their ‘buddies’ in climatology a favour in publishing this research(?) then they have been badly mistaken.

    Kevin Trenberth, climate analysis chief at the National Center for Atmospheric Research has said, “I remain somewhat skeptical. It is hard to make data where none exist.”

  15. Report this comment

    Olive Heffernan said:

    Malcolm,

    actually to quote Trenberth in full, he also said: “this looks like a pretty good analysis”.

    Olive

  16. Report this comment

    April Lorier said:

    Antarctica will, most definitely, melt into total exposure. New discoveries, now frozen under ice, will surprise the world. My question is this: How much will real estate sell for in the world’s biggest land-rush?

  17. Report this comment

    Eric Steig said:

    Responses to the various criticisms above (most of them specious) are available here, here, and here

  18. Report this comment

    John M said:

    Dr. Steig,

    It’s nice to see you make an appearance here.

    I’d like to pose a question to you that I’m pretty sure wouldn’t get through over at Real Climate.

    Although your corrected value for warming of all of Antarctica is 0.12 deg +/- 0.12 deg (“accounting for unresolved variance in mean reconstruction”), it’s been claimed at Climate Audit that your corrected method now shows that the warming for fully 50% of Antarctica is “not significant.” I know you don’t read Climate Audit (any more), so for your convenience, here is the link.

    http://www.climateaudit.org/?p=6712#comment-352035

    Could you comment on this?

    Thanks.